1. Field of the Invention
The present invention relates to a printed circuit board that can be suitably used in electronic devices including video cameras.
2. Description of the Prior Art
To describe a printed circuit board according to the prior art and its manufacturing method with reference to FIG. 9 through FIG. 12, an insulating board 21 consisting of a flexible substrate or the like has a rectangular base 22 provided with fixed contacts (not shown) or the like and a drawn part 23 having a substantially L-shaped overall form.
This drawn part 23 is substantially L-shaped to stay away from electrical parts or (not shown) or fitting members (not shown) arranged within the electronic device, and has insulating board angled parts 23a bent in an L shape or the like, cables 23b connected to both sides of, and formed in a width equal to, these insulating board angled parts 23a, and leaders 23c formed at an end of the cables 23b. 
A plurality of wiring patterns 24 made of silver have conductive pattern bent parts 24a shaped in an L or the like, linear wiring parts 24b connected to both ends of, and having a pattern with equal width to, these conductive pattern bent parts 24a, and linear connecting parts 24c provided at an end of the wiring parts 24b. 
The plurality of wiring patterns 24 are formed in parallel by screen printing over the drawn part 23 in a state wherein the conductive pattern bent parts 24a are arranged over the insulating board angled parts 23a of the drawn part 23 of the insulating board 21, the wiring parts 24b are arranged over the cables 23b and the base 22, and further the connecting parts 24c are arranged over the leaders 23c. 
The wiring parts 24b formed over the base 22 are connected to fixed contacts (not shown) formed of an electroconductive pattern over the base 22.
The wiring patterns 24 are so designed that the pitch of the patterns in the conductive pattern bent parts 24a be equal to the pitch of the patterns of the wiring parts 24b positioned close to and on both sides of the conductive pattern bent parts 24a, and that the gap width between the conductive pattern bent parts 24a be equal to the gap width between the wiring parts 24b positioned close to and on both sides of the conductive pattern bent parts 24a. 
On such a printed circuit board, the connecting parts 24c provided in leaders 23c are connected to a connector (not shown), so that a current from outside is entered into the printed circuit board via the connecting parts 24c or a current from the printed circuit board is supplied outside via the connecting parts 24c. 
By a manufacturing method for such a printed circuit board according to the prior art by screen printing, as shown in FIG. 11, after the insulating board 21 is mounted on a mount 25, a meshed printing mask 26 is mounted over the insulating board 21.
Next, after painting or otherwise applying silver paste 27 over the printing mask 26, a squeegee 28 is moved in the direction of arrow A to form the plurality of wiring patterns 24 over the insulating board 21 by printing.
Thus, as shown in FIG. 9 and FIG. 10, the squeegee 28 is moved in the direction of arrow A, and first the conductive pattern bent parts 24a are formed by printing, followed by the formation of the wiring parts 24b by printing.
The reason why the squeegee 28 is moved in the direction of arrow A is that the formation of the wiring patterns 24 by printing in a state in which their orthogonal intersections with the squeegee 28 are minimized results in minimization of the running or blurring of patterns. In particular, minimization of orthogonal intersections between the wiring parts 24b having large pattern areas and the moving path of the squeegee 28 serves to reduce the running or blurring of the patterns of the wiring parts 24b. 
However, while the conductive pattern bent parts 24a are printed earlier in an orthogonally crossing state than the wiring parts 24b by the movement of the squeegee 28 in the direction of arrow A, the silver paste 27 flows from the peak toward the trough of the ink permeating part of the printing mask 26 for the formation of the conductive pattern bent parts 24a during the printing of these conductive pattern bent parts 24a. 
If, then, the printing conditions lose balance, slight quantities of the silver paste 27 may get caught between the printing mask 26 and the insulating board 21 in corners of the trough of the ink permeating part, and create running parts 24d as shown in FIG. 10.
As a result, these running parts 24d would often short-circuit the wiring patterns 24 among themselves.
Or if in the conventional printed circuit board and its manufacturing method the squeegee 28 is moved in the direction of arrow B first to form the connecting parts 24c by printing and then the conductive pattern bent parts 24a are formed by printing after the wiring parts 24b are printed as shown in FIG. 12, blurred parts 24e of the silver paste 27 (see FIG. 12) may be caused to occur and possibly invite wire breaking in the conductive pattern bent parts 24a by stagnant air or the like gathering in the corners at the top of the ink permeating part of the printing mask 26 for forming the conductive pattern bent parts 24a. 
As printed circuit boards are required to be reduced in size along with the advance in the size compression of electronic devices in which they are to be used, the wiring patterns 24 are more narrowly spaced between one another and also reduced in width, running parts 24d and blurred parts 24e would give rise to the risks of short-circuiting and wire breaking in the resultant narrower conductive pattern bent parts 24a. 
In the conventional printed circuit board and its manufacturing method, since gaps between the conductive pattern bent parts 24a of the wiring patterns 24 are designed to be as wide as gaps between the wiring parts 24b positioned near their two sides and screen printing is carried out in the direction of arrow A, running parts 24d arise in the trough of the conductive pattern bent parts 24a, making the wiring patterns 24 susceptible to short-circuiting between each other.
Or if screen printing is carried out in the direction of arrow B, blurred parts 24e may arise at the top of the conductive pattern bent parts 24a, giving rise to the risk of inviting wire breaking.
In view of these problems, the present invention is intended to provide a more reliable printed circuit board less susceptible to short-circuiting or wire breaking in the conductive pattern bent parts of wiring patterns, and its manufacturing method.
According to a first aspect of the invention, the problems noted above are solved with a configuration having an insulating board and a plurality of wiring patterns formed over this insulating board by screen printing and provided with first conductive pattern bent parts and wiring parts linked to these first conductive pattern bent parts, gaps between adjoining first conductive pattern bent parts are formed wider than those between those of the wiring parts positioned close to and on both sides of the first conductive pattern bent parts.
According to a second aspect of the invention, a pitch of patterns in the first conductive pattern bent parts is formed greater than that of the patterns of those of the wiring parts positioned close to and on both sides of the first conductive pattern bent parts.
According to a third aspect of the invention, a pattern width in the first conductive pattern bent parts is greater than that of the patterns of those of the wiring parts positioned close to and on both sides of the first conductive pattern bent parts.
According to a fourth aspect of the invention, wiring patterns are screen-printed in such a printing direction that the first conductive pattern bent parts are formed by printing earlier than the wiring parts.
According to a fifth aspect of the invention, the insulating board has first insulating board angled parts and cables linked to both sides of these first insulating board angled parts, wherein a width of the first insulating board angled parts is formed greater than that of the cables, the first conductive pattern bent parts are positioned in the first insulating board angled parts, and a plurality of the wiring patterns are provided in a state in which the wiring parts are positioned in the cables.
According to a sixth aspect of the invention, the wiring patterns have second conductive pattern bent parts bent in a direction reverse to the first conductive pattern bent parts and wiring parts linked to these second conductive pattern bent parts, wherein a pattern width in these second conductive pattern bent parts is formed greater than that of those of the wiring parts positioned close to and on both sides of the second conductive pattern bent parts.
According to a seventh aspect of the invention, the wiring patterns are screen-printed in such a printing direction that the second conductive pattern bent parts are formed by printing after the wiring parts linked to the second conductive pattern bent parts are formed by printing.
According to an eighth aspect of the invention, a pitch of the patterns in the second conductive pattern bent parts is formed greater than that of the patterns of those of the wiring parts positioned close to and on both sides of the second conductive pattern bent parts, and gaps between adjoining ones of the second conductive pattern bent parts are formed wider than those between those of the wiring parts positioned close to and on both sides of the second conductive pattern bent parts.
According to a ninth aspect of the invention, the insulating board has second insulating board angled parts bent in a direction reverse to the first insulating board angled parts and cables linked to both sides of these second insulating board angled parts, wherein a width of the second insulating board angled parts is formed greater than that of the cables, and a plurality of wiring patterns are provided in a state in which the second conductive pattern bent parts are positioned in the second insulating board angled parts and the wiring parts are positioned in the cables.
According to a tenth aspect of the invention, the first insulating board angled parts and the second insulating board angled parts bent in a direction reverse to these first insulating board angled parts are formed adjoining each other, linked by the cables.
According to an eleventh aspect of the invention, there is provided a printed circuit board manufacturing method provided with a plurality of wiring patterns having first conductive pattern bent parts and wiring parts linked to these first conductive pattern bent parts, wherein the wiring patterns are screen-printed on an insulating board in such a printing direction that the first conductive pattern bent parts are formed by printing earlier than the wiring parts, and the gaps between adjoining ones of the first conductive pattern bent parts are formed wider than those between those of the wiring parts positioned close to and on both sides of the first conductive pattern bent parts.
According to a twelfth aspect of the invention, the pitch of patterns in the first conductive pattern bent parts is formed greater than that of the patterns of those of the wiring parts positioned close to and on both sides of the first conductive pattern bent parts.
According to a thirteenth aspect of the invention, the wiring patterns have second conductive pattern bent parts bent in a direction reverse to the first conductive pattern bent parts and wiring parts linked to these second conductive pattern bent parts, wherein the wiring patterns are formed by screen-printing the wiring parts on the insulating board in such a printing direction that the wiring parts linked to the second conductive pattern bent parts are formed by printing earlier than the second conductive pattern bent parts so that the pattern width in these second conductive pattern bent parts is formed greater than that of those of the wiring parts positioned close to and on both sides of the second conductive pattern bent parts.
According to a fourteenth aspect of the invention, there is provided a printed circuit board manufacturing method wherein the pitch of patterns in the second conductive pattern bent parts is formed greater than that of the patterns of those of the wiring parts positioned close to and on both sides of the second conductive pattern bent parts.
According to a fifteenth aspect of the invention, there is provided a printed circuit board manufacturing method wherein the first conductive pattern bent parts and the second conductive pattern bent parts adjoining these first conductive pattern bent parts are screen-printed on the insulating board in a state in which they are linked by the wiring parts.
According to a sixteenth aspect of the invention, there is provided a printed circuit board manufacturing method wherein a plurality of sets of the wiring patterns each consisting of the wiring patterns provided with the first and second conductive pattern bent parts and the wiring parts are formed by screen printing over a large insulating base.
According to a seventeenth aspect of the invention, there is provided a printed circuit board manufacturing method wherein the insulating board having a set of the wiring patterns is formed out of the plurality of the wiring patterns by punching out of the large insulating base.
According to an eighteenth aspect of the invention, there is provided a printed circuit board manufacturing method wherein the large insulating base is punched along the first and second conductive pattern bent parts, the first and second conductive pattern bent parts are positioned in first and second insulating board angled parts of the insulating board, and the wiring parts are positioned in a cable linked to the first and second insulating board angled parts of the insulating board.
According to a nineteenth aspect of the invention, there is provided a printed circuit board manufacturing method wherein the first and second insulating board angled parts are formed to have a greater width than that of the cable by punching out of the large insulating base.